CONSTRUCTION STAGE ANALYSIS OF SEGMENTAL CANTILEVER BRIDGE

Bridge is a structure which is usually built over several obstructions or depressions like rail lines, water bodies, highways, pipelines, canals and also urban roads for decreasing the traffic congestion and directing the traffic to desired destination. Cantilever construction is a method of progressive construction of a cantilever in segments and stitching them to segments previously casted by prestressing. Failure analysis of the bridge during construction phase is very essential, in balanced cantilever construction of continuous bridge, Bending Moment in the bridge increases with addition of the new segment during construction. Once the cantilever segments are added in to both side of pier, the bending moment arise in the pier is negative and increases with the addition of each new segment. When the key blocks are added, the bridge is converted from cantilever form to a continuous form and the negative bending moments on the pier decreases and there arises a positive moment. If the design of the bridge is carried out using the final construction stage structural factors only, it may fail during the intermediate stage. For this operation a bridge model is created and analysed to observe the rate of change of bending moment, reactions and deflection at different stages of construction including the time dependent effects in the construction sequence. The final stage results of the Segmentally constructed bridge is compared with the results obtained considering the bridge as a single structure neglecting the stage wise increments and the difference is noted to prove the importance of Construction Stage Analysis in a Segmental Cantilever Bridge .